Atomization of fluids is for instance carried out by mixing a fluid to be atomized with a gas. The use of a gas for atomization inevitably leads to introduction of this gas into the stream of atomized fluid, and in many practical implementations such a mix of fluids is highly undesirable. In connection with one of the aspects the present invention which relates to atomization of urea, atomization has previously been performed by use of pressurised air. In this connection it has been found that the presence of air will initiate growth of crystals which tend to block the flow passages. A further disadvantage is large air consumption.